In U.S. Pat. Nos. 3,883,333 and 4,158,557, continuous glass strand mat is shown being produced by traversing continuous strands across the width of a moving conveyor to provide a mat of a given depth. The mat is passed from the conveyor to a needle loom where it is punctured with barbed needles to entangle the strands to provide a mat having mechanical integrity. The strands of this mat are normally moisture laden as they are placed on the conveyor, i.e. moisture content of 10 to 20 percent or more, since as they are formed, they have an aqueous size applied to them. The mats prepared in the aforementioned patent have found particular utility in the production of fiber glass reinforced thermoplastic stamped parts. The size material utilized in coating the strands used to manufacture the mat are typically aqueous emulsions. The size disclosed in U.S. Pat. No. 3,849,148 being typical of the sizes employed.
In one modification shown in U.S. Pat. No. 4,158,577, mat is produced using forming packages as the strand source rather than fiber forming bushings. The forming package strands still have moisture on them though to a lower degree than the strands used in the bushing process i.e. (5 to 8 percent by weight being typical).
It has been found in the production of needled glass strand mat from wet, sized, continuous glass strand mats, the considerable production time is lost in cleaning of the needle looms used since they become fouled with glass and binder or size ingredients which are coated on the strands. A reduction or elimination of such production losses is therefore desirable.